Page 703 - Corrosion Engineering Principles and Practice

656 C h a p t e r 1 4 P r o t e c t i v e C o a t i n g s 657

1 6
3
9
ABRASIVE
7
2

11
10
5
Joe Blast 8

4

FIGURE 14.33 Typical rig for compressed air abrasive blasting: (1) an adequate and
efficient air supply (compressor); (2) air hose, couplings, and valves of ample size;
(3) a portable, high-production blast machine; (4) the correct size of antistatic
pressure hose with externally fitted quick couplings; (5) high-production venturi
nozzle; (6) pneumatic remote control valves for safety and cost savings; (7) an
effective moisture separator; (8) high nozzle air pressure; (9) the proper blasting
abrasive; (10) a safe air-fed helmet and air purifier; (11) inset showing bulk abrasive
storage hopper over pressure blast vessel equipped with remote control valves-
when pop-up filling valve opens, abrasive from the hopper fills the machine.

degrees of cleaning steel by blasting operations. These are described
briefly as follows:
1. NACE 1/SSPC 5: White metal blast cleaned—produces a gray-
white, uniform, metallic color with no obvious foreign
material remaining
2. NACE 2/SSPC 10: Near-white blast cleaned—foreign matter
is removed, but with differing shades of metallic gray surface
allowable
3. NACE 3/SSPC 6: Commercial blast cleaned—rust and foreign
matter is removed, except for tight specks of oxide or paint
uniformly distributed over a minor portion of the surface;
some residues in pits
4. NACE 8/SSPC 14: Industrial blast cleaned—similar to NACE
3/SSPC 6, except that evenly disbursed small islands of mill
scale are also allowed to remain on the cleaned surface.
5. NACE 4/SSPC 7: Brush-off blast cleaned—light mill scale and
tightly adhered rust is allowed if distributed over the surface.